package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.RedisData;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisClient;
import com.hmdp.utils.SystemConstants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Autowired
    StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedisClient redisClient;


    //这里需要声明一个线程池，因为下面我们需要新建一个现成来完成重构缓存
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    @Override
    public Result getShopById(Long id) {
        //缓存穿透
        Shop shopByIdWithCachePenetrate = redisClient.getShopByIdWithCachePenetrate(CACHE_SHOP_KEY, id, Shop.class, id1 -> getById(id1), CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //缓存击穿
        Shop shopByIdWithCacheBreakdown = redisClient.getShopByIdWithCacheBreakdown2(CACHE_SHOP_KEY, id, Shop.class, id1 -> getById(id1), CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //7.返回商铺信息
        return Result.ok(shopByIdWithCacheBreakdown);
    }


    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if(x == null || y == null){
            // 不需要坐标查询，按数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }

        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.MAX_PAGE_SIZE;
        int end = current * SystemConstants.MAX_PAGE_SIZE;

        // 3.查询redis、按照举例排序，分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().includeCoordinates().limit(end)
                );

        // 4.解析出id
        if (results == null){
            return Result.ok();
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>> > list = results.getContent();
        if (list.size() < from){
            return Result.ok();
        }
        // 4.1 截取from-end部分
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        List<Long> ids = new ArrayList<>(list.size());
        list.stream().skip(from).forEach(result ->{
            // 4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5.根据id查询shop
        String idsStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("order by field(id," + idsStr  + ")").list();
        for (Shop shop : shops) {
            String shopId = shop.getId().toString();
            shop.setDistance(distanceMap.get(shopId).getValue());
        }
        // 6.返回
        return Result.ok(shops);
    }

    /**
     * 缓存击穿--逻辑过期
     * @param
     * @return
     */
    public Shop getShopByIdWithCacheBreakdown2(Long id) {

        String key = CACHE_SHOP_KEY + id;

        //1.根据商铺id查询redis缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        //2.判断缓存是否存在
        if(StrUtil.isBlank(shopJson)){
            //3.未命中，直接返回null
            return null;
        }

        //4.命中
        //4.1将json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        //4.2将data转为shop对象
        JSONObject shopjson = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(shopjson, Shop.class);
        //4.3获取过期时间
        LocalDateTime expireTime = redisData.getExpireTime();
        //4.4判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //5.未过期，返回商铺信息
            return shop;
        }
        //6 过期，获取互斥锁，开启独立线程 缓存重建
        //6.1尝试获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        Boolean isLock = tryLock(lockKey);
        if (isLock){
            //6.2获取锁成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    this.saveShopToRedis(id,LOCK_SHOP_TTL);
                }catch (Exception e){
                    throw new RuntimeException(e);
                }finally {
                    //6.3释放锁
                    unLock(lockKey);
                }
            });
            //7.直接返回商铺信息
            return shop;
        }
        //8.未获取到锁，直接返回商铺信息
        return shop;
    }

    /**
     * 缓存击穿--互斥锁
     * @param
     * @return
     */
    public Shop getShopByIdWithCacheBreakdown(Long id) {

        String key = CACHE_SHOP_KEY + id;

        //1.根据商铺id查询redis缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        //2.判断缓存是否存在
        if(StrUtil.isNotBlank(shopJson)){
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }

        //如果查询到的是空字符串，说明是我们缓存的空数据
        if (shopJson != null){
            return null;
        }

        //4.缓存重建
        //4.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        Boolean isLock = tryLock(lockKey);
        //4.2判断是否获取锁成功
        if (!isLock){
            //4.3获取锁失败，休眠重试
            try {
                Thread.sleep(50);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return getShopByIdWithCacheBreakdown(id);
        }
        //4.4获取成功根据id查询数据库
        //获取锁成功再次检测redis缓存是否存在，如果存在直接返回，不存在就创建
        String shopJson1 = stringRedisTemplate.opsForValue().get(key);
        //判断缓存是否存在
        if(StrUtil.isNotBlank(shopJson1)){
            //存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }

        //如果查询到的是空字符串，说明是我们缓存的空数据
        if (shopJson != null){
            return null;
        }
        //不存在，根据id查询数据库
        Shop shop = getById(id);

        if(shop == null){
            //不存在，缓存空字符串
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }

        //4.5.存在，写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //4.6释放互斥锁
        unLock(lockKey);
        //5.返回商铺信息
        return shop;
    }

    /**
     * 缓存预热
     */
    public void saveShopToRedis(Long id,Long expireSeconds){
        //1.查询店铺数据
        Shop shop = getById(id);

        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));

        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }


    /**
     * 加锁
     */
    public Boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(flag);
    }

    /**
     * 释放锁
     */
    public void unLock(String key){
        stringRedisTemplate.delete(key);
    }


    /**
     * 缓存穿透
     * @param
     * @return
     */
    public Shop getShopByIdWithCachePenetrate(Long id) {

        String key = CACHE_SHOP_KEY + id;

        //1.根据商铺id查询redis缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        //2.判断缓存是否存在
        if(StrUtil.isNotBlank(shopJson)){
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }

        //如果查询到的是空字符串，说明是我们缓存的空数据
        if (shopJson != null){
            return null;
        }

        //4.不存在，根据id查询数据库
        Shop shop = getById(id);

        if(shop == null){
            //5.不存在，缓存空字符串
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }

        //6.存在，写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //7.返回商铺信息
        return shop;
    }



    @Override
    @Transactional
    public Result updateShopById(Shop shop) {
        if(shop.getId() == null){
            return Result.fail("店铺id不能为空");
        }
        Long id = shop.getId();

        //1.从数据库中更新数据
        updateById(shop);

        //2.更新缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        //3.返回结果
        return Result.ok();
    }
}
